The x-ray crystal structure of thiamine hydroiodide,C1ZH18N40S12'
has been determined. The unit cell parameters are a = 13.84 ± 0.03,
o
b = 7.44 ± 0.01, c = 20.24 ± 0.02 A, 8 = 120.52 ± 0.07°, space group
P2/c, z = 4. A total of 1445 reflections having ,2 > 2o(F2), 26 < 40°
were collected on a Picker four-circle diffractometer with MoKa
radiation by the 26 scan technique. The structure was solved by the
heavy atom method. The iodine and sulphur atoms were refined
anisotropically; only the positional parameters were refined for the
hydrogen atoms. Successive least squares cycles yielded an unweighted
R factor of 0.054. The site of protonation of the pyrimidine ring is
the nitrogen opposite the amino group. The overall structure conforms
very closely to the structures of other related thiamine compounds.
The bonding surrounding the iodine atoms is distorted tetrahedral. The
iodine atoms make several contacts with surrounding atoms most of
them at or near the van der Waal's distances
A thiaminium tetrachlorocobaltate salt was produced whose
molecular and crystal structure was j~dged to be isomorphous to
thiaminium tetrachlorocadmate.